Why are wasps dumping their pupae?

[cimbalom]

I have a wasps nest under my house (they don't bother me), and in the last week or two the wasps have been coming out carrying pupae, which they abandon on the steps. Are they trying to carry them to another nest, or are they trying to get rid of them? The pupae are as big as them, so it's a hard job. Why do they do it?

[MrIxolite]

They are worshipping you as their god. Sacrificing their young on the alter of your doorstep.....maybe

[Dr Doolittle]

Without knowing which part of the world you live in cimbalom, I suspect if the nest is under your house (rather than under the eaves of the house), it has probably been invaded by ants who will happily march into a wasp nest and begin devouring the pupae. It's more likely that the adult male wasps were taking the pupae to another nest rather than dumping them. But as you rightly point out, the weight of nearly grown wasp pupae make it extremely difficult to 'transport' them. As a result, no doubt many will have been dropped during the 'rescue mission'. Such is nature!

[Dr Doolittle]

I should add that wasps (believe it or not) are quite intelligent. So much so that if disease or illness finds it's way into the nest, they WILL remove the ailing and/or diseased pupae in order to protect/preserve the uninfected ones. So in that respect, they might well have been 'dumping' the pupae as you intimated in your question. Again, such is nature. It's only we humans in the animal/insect/mammal world (with the notable exceptions of whales, dolphins, elephants and certain apes) who will try to intervene in the course of nature.